AWWA WQTC60634

The State of California Department of Water Resources (DWR) applies copper sulfate bimonthly, from April through September, to control algae in the South Bay Aqueduct (SBA). During this time, water quality measurements are performed on both source and finished waters at the Santa Clara Valley Water District's drinking water treatment plants. The interpretation and assessment of this water quality data then provides management and operational staff the information necessary in making appropriate source water and/or treatment decisions. The following test parameters are analyzed to determine source and finished water quality before and after the application of copper sulfate in the SBA: Turbidity, threshold odor number (TON), fluorescence, flavor profile analysis (FPA), 2-methylisoborneol (MIB), trans-1,10-dimethyl-trans-9-decalol (geosmin), total organic carbon (TOC), dissolved organic carbon (DOC), pH, color, temperature, conductivity, phosphate, nitrate, and examination and enumeration of algae. However, after applying copper sulfate and testing for potential taste and odor indicators, the District still experienced a severe taste and odor incident, which caused water quality management to change source and treated water operations significantly. The District responded by conducting more frequent flavor profile analyses, reducing the flow of the affected source water, feeding more powder activated carbon, and blending the affected source water with a cleaner water source. Additionally, the DWR increased the frequency of copper sulfate to eliminate the taste and odor producing algae. As a result of these actions, the taste and odor incident subsided through a coordinated effort from the District's maintenance, operations, water quality, and laboratory services as well as through communication among DWR, District retailers, and the District. Therefore, this study evaluates how water quality management addressed the taste and odor incident through optimizing source and treated water operations as well as addresses the communication efforts necessary in dealing with the problem of taste and odor compounds and consumer complaints. Finally, this study provides decision making tools and water treatment strategies that other utilities may find useful when responding to a taste and odor event. Includes 11 references, table, figures.